Rafael Nadal has not ruled out a return to the court before the end of the 2012 season, but has admitted the prospect of playing before 2013 remains remote.

The 11-time grand slam champion, who has not played since his shock second-round defeat by Lukas Rosol at Wimbledon, has been swimming and working in the gym in an effort to prepare his knees for a return to competitive action.

But while the 26-year-old believes he has turned a corner in his recovery, he insists that he has not targeted an event for his return.

"Impossible, no. But difficult, yes," Nadal said of a return before the new year. "I want to go day by day. I go every day to the gym, the swimming pool. I am trying not to think that far.

"I am feeling a little bit better now than the first couple of months. It has been very, very tough for me because I feel my knee didn't improve in the right direction, but today is something different. The last couple of weeks the improvement of my knee is something I really can feel."

With the ATP World Tour Finals at The O2 in London and the Davis Cup final, where Spain face the Czech Republic, both coming up in November, Nadal has more than most to aim for at the end of the season.

But the Spaniard refuses to commit himself before he believes his long-standing knee problem is under control and he is back at his best with a racket in hand.

"I will need a period of time to practise," he said. "I don't know if that will take a few weeks or one month and a half."

In spite of the second lengthy lay-off taken to rest his knees, Nadal is adamant that he cannot change his approach to either his playing style or the schedule of tournaments he plays if he is to stay at the top of the sport.

"I can make a few adjustments, but not much," he said. "It's very difficult to think about a completely different calendar for me."